Quality and Quantity!

International competition is challenging foundries. They have to produce faster and faster, better, cheaper. Automatic Foundry Solutions offers complete solutions for core production, from core shooting machines to robust core boxes. MAGMA C+M is used to design both core shooters and core boxes. The specialized software supports companies by simulating all process steps of core manufacturing. The result is an optimized solution for the foundry. It is thus possible to reliably master the balancing act between cost and quality.

Botini is a manufacturer of machines and equipment, particularly for the food industry. The required castings are produced in its own foundry. In the foundry, further improvement of existing production processes is part of day-to-day business. The driving factors are quality requirements and costs. If production changes are made, the entire process chain must be analyzed and optimized with regard to the respective requirements. The initial situation for a gray cast iron “support” weighing 1.5 kg was as follows: Four castings each were produced in one mold level. Three mold levels were stacked upon each other. They were connected via the casting system to form the entire mold. This arrangement allowed pouring 12 castings simultaneously, with a yield of 73 %. One limiting factor was that the core elements required for stacking the levels were manufactured manually. The limited possibilities for achieving uniform and high-density compaction of the sand necessitated increased wall thicknesses to attain the required mechanical strength. The reproducible compactibility of the sand and the achievable mechanical strength limited stacking to no more than three levels (Fig. 1).

To achieve higher mechanical strength and optimize both material consumption and cycle times, Botini considered automating the core production with a core shooter. These considerations were discussed with Automatic Foundry Solutions. For Botini, the decisive factor in selecting the machine manufacturer was the ability to quickly establish a robust and cost-effective production process without the necessity to build up their own experience.

The concept of Automatic Foundry Solutions is to offer an integrated engineering approach to its customers. The development of individual process steps is fundamentally based on the requirements of the castings. The development of the overall process includes all the necessary information, such as machine, core box, both production and stacking of the mold levels, casting system design, casting process, etc.

A decisive criterion for the development and testing of the core box was to reduce overall costs, including the investment in a core shooter. Transitioning to mechanical core production involved a redesign of the mold parts, a reduction of the wall thicknesses and adjustments to the outer contour in particular.

MAGMA C+M: The Right Tool for Designing the Suitable Core Box

When designing the core box, it was soon decided that a vertically parted core box layout was the best solution. For the initial design, three larger shoot nozzles were evenly distributed. Thanks to the expertise of Automatic Foundry Solutions, core box vents were positioned in the same way (Fig. 2).

With MAGMA C+M, core shooting and core curing were calculated and evaluated for this first design. The core box design proved the basic feasibility of core shooting, but also revealed some weaknesses. Although completely filling the contoured upper area was possible, the sand compaction between the nozzles tended to be too low (Fig. 3).

During pouring, these differences in density would lead to surface defects in the casting or even to metal leaking from the mold in the event of breakage. The middle nozzle was dimensioned in such a way that the sand hit parts of the contour during core shooting, which would typically result in increased core box erosion (Fig. 4).

Positioning core box vents in such a way as to accommodate both core shooting and core curing is often difficult. In this case, while vents in the upper core box area supported the compaction of the sand in critical locations, for gassing, it was more important that catalytic amine also reached the lower core box areas as quickly as possible. A larger number of core box vents in the upper part of the core box prevented amine from efficiently reaching all areas located in the lower core box regions (Fig. 5). For core curing, a disproportionately large amount of amine and a relatively long gassing time were required.

After systematic testing of a number of simulation-led modifications, a compromise was worked out, leading to excellent shooting results, while also ensuring effective core gassing. The three large shoot nozzles were replaced by seven smaller nozzles. As a result, the sand in the mold was compacted more uniformly and with a higher density, especially near the shoot nozzles (Fig. 6). The smaller shoot nozzles also ensured that the core box surface suffered only minor erosive wear from the sand flow.

Reducing the number of core box vents in the upper area improved the amine flow throughout the core box. In a short time, amine could now also reliably flow through the lower core areas (Fig. 7).

Automated Processes – Better Processes?

Automatic Foundry Solutions has developed a core box for Botini that allows producing good cores right from the start with the equally newly developed core shooter. The cores now have higher mechanical strength, while sand consumption has been reduced. The binder content has been significantly reduced for the automated core production. Instead of 2 ml, now only 0.7 ml of amine is required per kg of core sand, with a shorter gassing time of 10 s instead of 30 s. The higher core density and the improved core surface now allow the stacking of five mold levels in one mold. This has increased the yield from 73 % to 90 %.

20 at One Go – Botini Now Produces Even More Efficiently

In most cases, the optimum nozzle configuration varies for core shooting and for efficient gassing. The experts at Automatic Foundry Solutions have the right tool: With MAGMA C+M, they found the ideal solution for both. They thus designed a more robust and efficient process – in terms of cycle time and material consumption as well as in terms of quality. For the customers of Automatic Foundry Solutions – not just for Botini –, this means a lower environmental impact, less energy consumption and waste, as well as advantages in international competition.

This benefits both sides: Botini managed to successfully automate the process, safeguard the investment and quickly amortize costs. Automatic Foundry Solutions managed to offer its customers both the optimal core shooter and the best core box – for Automatic Foundry Solutions itself, MAGMASOFT® is the best tool.